The present invention relates to a new and improved heating and ventilation system of the type comprising a so-called heat pumping device for converting low-temperature heat energy into high-temperature heat energy useful for e.g. heating objects and spaces surrounded by a preferably heat insulated outer covering, such as rooms in a building.
Heat pumping devices of various designs have for a long time been used for converting readily available low-temperature heat energy--for example the low-temperature heat energy contained in cold air, cold water or in the ground during winter time--into a condition of higher temperature, useful for heating purposes. As is well known in the art heat pumping devices basically consist of a closed circuit having means for compressing a heat conveying fluid, condenser means for condensing said fluid, means for expanding said fluid, and means for evaporating said fluid. The evaporator means are in heat exchanging contact with a fluid or a body containing heat energy of a comparatively low temperature, which is absorbed by the heat carrying fluid of the heat pumping device by causing the heat carrying fluid to evaporate at a reduced pressure and a low temperature. After having passed through the evaporator means, said heat carrying fluid is compressed by the compressor means to raise the pressure and the temperature thereofto the desired higher level, and it is then fed into said condenser means, which is in direct or indirect heat exchanging contact with the object or space to be heated. When the heat is thus absorbed from the heat carrying fluid, the same will be condensed within said condenser means. Thereafter, the heat carrying fluid is expanded in said expansion means to a reduced pressure and to a temperature lower than that of the fluid or body supplying the low-temperature energy. The heat carrying fluid is then returned to the evaporator means for absorbing further low-temperature energy, and the cycle is repeated.
The function of a heat pumping device is thus, in short, to raise the temperature of a quantity of energy. The smaller this raise of the temperature has to be, the smaller amounts of expensive energy will be required for attaining the higher temperature level, i.e. for operating the said compresser means. It has until the present invention been assumed that, as an example, it would be necessary to raise the pressure and the temperature of the heat carrying gas in the compressor means to such a high level, that the coldest part of the condenser means will have a temperature of at least 20.degree. C. in order to raise the temperature of air flowing through a conventional cooler having a built-in condenser from 0.degree. C. to 20.degree. C. (In this example the condensation probably takes place between +35.degree. C. and +25.degree. C.) The temperature of the gas immediately after the compression is also much higher because of inevitable overheating of part of the gas. Similar considerations, although reversed as to the temperature conditions, apply to the evaporator means of the heat pumping device, wherein an evaporation temperature is assumed and chosen, which in total is lower than the lowest temperature of the low-temperature energy, in spite of the fact that a great pat of this energy at the start has a considerably higher temperature.